1. Field of the Invention
The present invention relates to an electrostatic flocking apparatus for electrostatically applying flock to a piece of work having an adhesive layer formed thereon (hereinafter referred to as the workpiece) when the workpiece is passed through an electrostatic flocking chamber at high speed in a condition in which the workpiece is electrically grounded, so that a so-called “electrostatic flocking process” is conducted, wherein the flocking process is followed by a drying process serving as an after treatment as is in ordinary process conducted to produce a flocked product.
2. Description of the Related Art
An electrostatic flocking apparatus has an essential construction in which: a flocking electrode for creating a high voltage electrostatic field is supported inside a housing through an insulation member, wherein the housing forms an electrostatic flocking chamber; a workpiece is oppositely disposed from, i.e., space a certain distance apart from the flocking electrode, and electrically grounded in a condition in which the workpiece is coated with an adhesive layer and disposed either above or below the flocking electrode, or disposed in the same plane or level as that of the flocking electrode; the electrostatic field is created between the flocking electrode and the workpiece, so that short fibers or fibrils are electrostatically floated and driven to fly parallel to the electric lines of force in the electric field toward the workpiece, whereby the short fibers are implanted in the adhesive layer of the workpiece. Then, the workpiece is subjected to an after treatment through which the workpiece is dried to become a flocked product. In fabrication, it is not unusual for the workpiece to be electrically grounded when the workpiece is supported on a shelf or suspended from an appropriate suspension member, provided both the shelf and the suspension member are electrically grounded. Further, it is also not unusual for the workpiece to be moved from an inlet opening of the housing to its outlet opening in a condition in which any supporting member for supporting the workpiece is used.
Provided in a ceiling portion of the housing is a ventilating apparatus provided with a filter, which filter prevents the floating short fibers from escaping outside from the housing in the electrostatic flocking operation.
Disposed on the side of the inlet opening of the housing is an adhesive applicator apparatus for applying an adhesive to a surface of the workpiece to form an adhesive layer thereon, through the adhesive applicator apparatus the workpiece is introduced into the housing.
Disposed on the side of the outlet opening of the housing is a drying apparatus for drying the flocked workpiece to perform an after treatment thereof when the flocked workpiece passes through the drying apparatus.
The drying apparatus is provided with: a heating unit for drying the adhesive layer having been formed on the surface of the workpiece; and, an exhaust port for discharging vapors or moisture contained in the adhesive layer of the flocked workpiece.
The drying apparatus is followed by a product receiving apparatus which receives the flocked products.
Now, the electrostatic flocking operation of the workpiece performed in a conventional electrostatic flocking apparatus will be described using a system called “up-system” as an example, in which up-system a short fiber reservoir portion is disposed below the housing.
The so-called “workpiece” is prepared by the use of the adhesive applicator apparatus disposed in front of the inlet opening of the housing, in which applicator apparatus an adhesive is applied to the surface of a piece of work being electrostatically flocked, so that an adhesive layer is formed on the work, whereby the work having been coated with the adhesive layer, i.e., the so-called “workpiece” is prepared.
The thus prepared workpiece having the adhesive layer formed thereon is supported by a member having been electrically grounded, introduced into the housing through the inlet opening thereof, and disposed inside the housing. In other words, the workpiece is disposed inside the housing in a condition in which the workpiece is electrically grounded.
At this time, a high-voltage is applied to the flocking electrode so that a high voltage electrostatic field is created. Consequently, due to the presence of this electrostatic field, electric lines of force extend from the flocking electrode to the electrically grounded workpiece.
A moisture bearing air is blown from the outside into the reservoir portion so that the short fibers having been stored in the reservoir portion are floated in the electrostatic field. Due to this, the short fibers thus floated in the housing are electrically charged and therefore strongly driven to rush for the workpiece. As a result, the short fibers have their front end portions stuck into the adhesive layer having been applied to the surface of the workpiece, so that the entire surface of the adhesive layer is uniformly covered with the short fibers.
Floating short fibers, which are left over to form excess fibers, reach the ceiling portion of the housing, and are trapped in a filter disposed in the ceiling portion of the housing, while the moisture bearing air is discharged to the outside through an exhaust unit.
The workpiece having subjected to the above operations emerges from the housing through its outlet opening, and then passed through the drying apparatus provided with the heating unit so that the moisture contained in the adhesive of the adhesive layer is evaporated, whereby the short fibers thus stuck in the adhesive layer are firmly implanted in the workpiece in this state.
After completion of the above process, the workpieces (i.e., completed products) are collected.
Consequently, in order to apply flock to the workpiece in the housing, it is necessary for the adhesive layer formed on the surface of the workpiece to have an appropriate viscosity which enables the front end portions of the short fibers (flock) to easily stick into the adhesive layer, wherein the short fibers always fly from the electrode to the workpiece in the housing. In other words, it is necessary for the adhesive layer to be always wet so as to keep its appropriate viscosity described above.
However, the interior of the housing is often heated to increase in temperature when the flocking operation is performed in the housing. Due to this, the moisture in the adhesive layer formed on the workpiece tends to evaporate. Such evaporation of the moisture results in formation of a stressed skin on the adhesive layer, which makes it difficult for the front end portions of the short fibers to stick into the adhesive layer. Consequently, under such circumstances, it is impossible to obtain good quality flocked product even when the workpiece is subjected to the electrostatic flocking operation.
Further, the short fibers floating in the housing tend to escape out of the housing through its inlet and its outlet opening under the influence of the air blown during the electrostatic flocking operation. This is one of disadvantages of the conventional housing. In order to prevent the short fibers from escaping out of the housing through its inlet and its outlet opening, an air curtain unit is provided in each of the inlet and the outlet opening of the housing.
However, heretofore, there is no idea that a suitable device for surmounting the above disadvantage should be provided in the housing. More specifically, there is no idea that such device should be realized by modifying the air curtain unit in a manner such that the air curtain unit also serves as the above device.